Mold dressing



V Paiented May 13', 1941 I 1 UNITED STATES PATENT OFFICE MOLD DRESSING Worth Gray, Wheaton, and Frederick H1 MacLaren, Calumet City, 111., assignors to Standard Oil Company, Chicago, 111., a; corporation of Indiana No Drawing. Application December .18, 1939,

Serial No. 309,826

p 12 Claims. (Ci. 22-189) i The present invention relates to improvements We have discovered that the foregoing objects in mold dressings and in particular to improvecan be attained by employing as the vehicle for ments in non-ferrousmetal. mold dressings. mold dressings a refined mineral oil of the cor- In the preparation of metal ingots the molten"{ rect volatility characteristics and low carbon metal is poured into molds and permitted to residue compounded with from about 1% to about solidify. To prevent the adhesion of the metal 25% and preferably from about 4% to about to the walls of the mold it is the general foundry of naphthenic acid and/or anaphthenic acid practice to apply a so-called dressing to the \derlvative. The mineral oil employed is preferinterior surface of the mold. The mold dressing ably one having approximately the following must be a material which adheres to thesurface 10 characteristics: of the mold prior to and throughout the pouring saybolt Universal viscosity at period and must volatilize at a sufficiently high rate after the molten metal comes in contact with Flash point. 3 the dressing to assure complete evolution of the Conradson I 05 gases formed before the metal solidifies. If the 5. latter property is not present the solidified metal The "Petroleum Oil p y d n add on to havwill be porous. Furthermore the dressing vehicle 8 the b e characteristics Should Preferably must not leave a substantial dislodgable residue be a narrow cut Y this e mean e upon evaporating since this residue, mainly caroil should not be one in which a high viscosity bonaceous mattgn'fiogtg t th surface of the '20 oil is blended with a low viscosity oil' to obtain solidifying ingot and forms what is known as a a blended oil having the desired viscosity falling dirty ingot. This is highly unde i bl when within the above viscosity range. working with non-ferrous metals such as brass, Although for summer use the p p t o e bronze and other copper bearing metals since it 011 is unimportant, for Winter use it is highly necessitates the cutting up of the ingotln Order sirable to use an oil having a maximum pour to eliminate the dirty portion. point of about 35 F. If necessary a suitable Mold dressings heretofore employed have con-- D P n p sor, uch as Pourex, described sisted essentially of a mixture of lard oil and in Patents 1,963,917 nd 6 8, may be graphite having a pasty consistency. In some added to lower the P Point Of t instancesa diluent such as kerosene has been The p ihenic acids employed may be obemployed with the lard oil-graphite mixture. mined from any ur e al ou h we preier to Attempts to utilize petroleum oils in place of the employ nephthenie c ds O t ned from petrolard oil have not heretofore been successful. leum s- The nflphiihenie acids y be recov- The primary object of the present invention is ered from petroleum oils either by treating the t r i a ld dressing um m petroleum oils with aqueous alkali at elevated temperatures, oil vehicle. Another object of the invention is acidifying iihe p ed or extracted solution of to provide an improved mold dressing which will alkali naphthenaiies, extracting w t a 10w boiladhere to the sides of the mold throughout the s Solvent and separating h acid by fractional pouring operations. Still another object of the distillation, the oil may be distilled in the invention is to provide apetroleum oil vehicle P e of an alkali and the resulting p for mold dressings which will volatilize at a suiiicovered by extraction With c l of about ciently high rate after the molten metal contacts r hother methods are described in Ellis the dressing to assure complete evolution of the The Chemistry of Petroleum Derivatives, vol. gases formed before the metal solidifies. A fur- 2, page 1104 et seq- In place of the nap ther object is to provide an improved petroleum acids W e e soaps f p e' acids, oil vehicle for mold dressing which will not leave p rticularly the alkali metal soaps such as soa substantial residue upon evaporation. Other dium naphthenate or potassium naphthenate, objects and advantages of the invention will bealthough the alkaline earth metal and the heavy come apparent from the following description metal soaps of naphthenic acids also may be thereof. 0 employed.

In preparing the mold dressing the compounded oil is miited-with from about to about 40% graphite in form a paste or paste-like material which is applied tothe interior surfaces of the mold.

The following formula is exemplary of a preferred composition employed in preparing brass mold dressings:

Naphthenic acids "per cent 4 to '10 Mineral oil do 90 to 96 Mineral oil characteristics Saybolt Universal viscosity at 100 F seconds 180 to 190 Flash (minimum) F 390 The above compounded oil is then mixed with from about 15% to about 40% oil graphite or other suitable solid material such as for example whiting, vermiculite and the like, and the resulting paste applied to the mold.

Although our invention has been described by specific embodiments thereof it is not intended that these shall be regarded as limitations upon the scope of the invention, except insofar as included in the appended claims.

We claim: v l. A dressing for molds receiving a molten metal comprising a mineral oil having a Saybolt Universal viscosity at 100 F. between about 100 seconds and about 300 seconds, a flash point of from about 375 F. to about 450 F., and a Conradson carbon of not more than about 0.5 and an added minor proportion oi a compound selected trom the group consisting 025a acid and a metal naphthenate'. V

2. A dressing for molds for casting nonferrous metals comprising a mineral oilhaving a Say-- bolt Universal viscosity at 100 F. between about 100 seconds and about 300 seconds, a flash point of from about 375 F. to about 450 F. and a Conradson carbon of not more than 0.5 and from about 1.0% to about 25% of naphthenic acid.

3. A dressing for molds for casting copper bearing metals comprising a mineral oil havlng a Saybolt Universal viscosity'at 100 F. between about 100 seconds and about 300 seconds, a flash point between about 375 F. and 450. F. and a Conradson carbon less than about 0.5, and .a

minor amount or naphthenic acid.

4. A dressing formolds as described in claim 3 in which from about 4.0% to about 10% of naphthenic acids are employed.

5. A dressing for molds for casting brass comprising a mineral oil having a Saybolt Universal idscosityat 100 F. between about 180 seconds and lfio seconds. a flash point greater than about 390 F. and a Conradson carbon. less than about 0. and from about 4% to about 10% of naphthenic acids. v

. 6. The method of treating a mold preparatory naphthenic to receiving a molten metal therein comprising applying to the interior surfaces of the mold a mold dressing comprising a mineral oil having a Saybolt Universal viscosity at 100 F. between about 100 seconds and about 300 seconds, a flash point 01' from about 375 F. to about 450 F., and a Conradson carbon of not more than about 0.5 and an added minor proportion of a com- ..pound'-se1ected from the group consisting of a naphthenic acid and a metal naphthenate.

7. The method oi. treating a mold preparatory to receiving a molten non-ferrous metal therein, comprising applying to the interior surfaces of the mold a mold dressing comprising a mineral oil and from about.l.0% to about of naphthenic acids.

8. The method of treating a mold'as described in claim 7 in which the mineral oil of the mold dressing has the following approximate specifications:

Saybolt Universal viscosity at 100 F seconds 100 to 300' Flash point F. 375 to 450 Conradson carbon Maximum of 0.5

' 9. The method of treating a mold preparatory to receiving-a molten non-ferrous metal therein comprisingapplying to the interior surfaces of the mold a mold dressing comprising a mineral oil and from about 4.0% to about 10% of naphthenic acid.

V 10. The method of treating a mold preparatory to receiving molten brass therein compris- "ing applying to the interior surfaces of the mold a dressing comprising a mineral oil having a 'Saybolt Universal viscosity at F. between about seconds and about seconds, a flash point greater than about 390 F. and a Conradson carbon less than about 0.5 and from about 4% to about 10% of naphthenic acids.

11. A dressing for molds receiving a molten metal comprising a compounded mineral oil,

anda solid selected from the group consisting of graphite, whiting and vermiculite, said r compounded 011 comprising a mineral oil having a'Saybolt Universal viscosity at 100 F. between about 100 seconds and about 300 seconds and a flash point of from about 375 F. to about 450 F.

and an added minor amount of naphthenic acids.

12. A dressing for molds for casting brass comprising a compounded mineral oil and from about 15% to about 40% graphite, said compounded oil comprising a mineral oil having a Saybolt Universal viscosity at 100 F. between aboutlOO secondsand 300 seconds and a flash point from about 375 F. to about 450 F. and from about1.0% to about 25% naphthenic acids.

WORTH GRAY. FREDERICK H. MACLAREN. 

